1. Field of the Invention
The present invention relates to a data-processing device which receives data transmitted from another data-processing device provided on a network, a method of controlling the data-processing device, and a program.
2. Description of the Related Art
In recent years, data-providing services using the Internet have been developed and are available for enabling users to share data. Data-providing services may allow for uploading image data to a server and notifying other users of the uniform resource locator (URL) of an image-storage location through an electronic mail or the like so that the notified users on the Internet can share the uploaded image data. Further, data-providing services are available that allow for storing a single album including a plurality of image-data items that are transferred from a user and that are associated with one another and releasing the album. According to an example release service, upon being notified that the album is released, another user can see the album by using a personal computer (PC) and/or a mobile information-communication terminal according to details on the notification.
The above-described services allowing the users to see and share the image data or the like have been achieved by using client-server systems including a server that provides information and a client that receives the information transmitted from the server. In the client-server system, the relationship between an information server and an information recipient can be clearly perceived. Further, in the client-server system, a heavy load is often placed on the information server and management of the information server often requires complicated procedures.
For solving the above-described problems of the client-server systems, peer-to-peer (P2P) systems have been proposed. The P2P system does not require the devices and/or apparatuses corresponding to the server and/or the client used in the client-server system, but includes a plurality of peers having functions of both the server and the client. In the P2P system, the information server and the information recipient are equivalent with each other and processing loads are scattered over the entire network.
There has been proposed a “Napster (Registered Trademark)” system, as one of known P2P systems. The Napster system allows for exchanging music data between private users via the Internet so that any user can obtain the music data. In the Napster system, a PC of the user is connected to a central server managed by Napster Inc. and a list of speech files stored in the user's PC is transmitted to the server. The music-file list is shared by Napster users so that any one of the users can search for a music file held by another user and download the searched music file. The central server only provides file-search databases and/or controls user connections. The music data is transmitted and/or received between computers of the users, where the computers are directly connected with one another. After the “Napster” system was released, a “Gnutella” system was released. The Gnutella system does not require the device and/or apparatus corresponding to the central server used in the Napster system. Namely, all of data items are directly transmitted and/or received between the computers of users in a bucket-brigade manner.
Thus, there are at least two types of P2P systems including a hybrid-type P2P system and a pure-type P2P system. In the hybrid-type P2P system, data is transmitted and/or received via the medium of the central server. In the pure-type P2P system, the data is transmitted in the bucket-brigade manner.
United States Patent Application 20040172440 discloses a technology relating to an example system that allows for seeing and sharing data by using the above-described P2P systems. Namely, United States Patent Application 20040172440 proposes an environment where users can share image data by using a P2P network. According to the technology disclosed in United States Patent Application 20040172440, upload processing is not required and any user can easily obtain a print with desired finished quality at a nearby laboratory shop.
Thus, according to the frequently used client-server-type data sharing systems, heavy loads are placed on the information server and/or the server management requires complicated procedures. However, since all of the data items shared by the users are uploaded to the server, and a manager strictly manages the server so that the data sharing system can operate with stability, the users can access the server and see the data items at any desired time.
In the P2P data-sharing systems, the data items shared by the users are not uploaded to the server, but stored in data-sharing devices of the users. Further, the data-sharing devices of the users are not necessarily connected the network at all times. Therefore, it may be difficult for the user who wants to see the data items to see the entire data items existing in the data-sharing system at all times.
Further, when a link is established between data items existing in the data-sharing system and the data items are associated with each other, it is difficult to provide the entire data items at all times, which causes an error such as link disconnection.